Construction of a chiral quaternary carbon center by indium-catalyzed asymmetric α-alkenylation of β-ketoesters
Construction of a chiral quaternary carbon center by indium-catalyzed asymmetric α-alkenylation of β-ketoesters
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DOI：
10.1021/ja710408f
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发表时间：
2008-04-02
影响因子：
15
通讯作者：
Nakamura, Eiichi
中科院分区：
文献类型：
--
作者：
Fujimoto, Taisuke;Endo, Kohei;Nakamura, Eiichi
通过铟（III）催化的手性烯胺与1-炔的非对映选择性α-烯基化反应，在β-酮酯的α-位上构建了非外消旋的全碳季铵立构中心。将带有来自L-异亮氨酸的手性助剂的烯胺加入到炔中，以优异的收率和优于90%ee的立体选择性得到α-烯基化产物。人们可以将高选择性归因于涉及助剂和金属原子的螯合中间体和铟（III）原子与炔之间的高效相互作用。选择性随着反应温度升高至120 ° C而增加，并且在更高温度下降低。
Construction of a nonracemic all-carbon quaternary stereocenter at the a-position of beta-ketoesters was achieved by way of an indium(III)-catalyzed diastereoselective alpha-alkenylation reaction of chiral enamines with 1-alkynes. The enamine bearing a chiral auxiliary derived from L-isoleucine was added to the alkyne to give an alpha-alkenylated product in excellent yield and with a stereoselectivity better than 90% ee. One can ascribe the high selectivity to a chelate intermediate involving the auxiliary and the metal atom and the high yield to efficient interactions between the indium(III) atom and the alkyne. The selectivity increased as the reaction temperature was raised to 120 degrees C and decreased at higher temperatures.